“…The idea of arresting flows for reliable design and fabrication of self-organized patterns indeed goes far beyond the specific phenomena and liquids discussed in this Perspective. This burgeoning movement is targeting a broad range of phenomena to develop moldless methodologies for assembling optical components, porous materials, textiles, pharmaceutical particles, and fractal and chaotic structures. − This type of approach is potentially applicable to a broad range of liquids from commodity/engineering materials (e.g., thermoplastics/thermosets), to innovative materials such as responsive hydrogels and liquid crystal elastomers, to UV curable solutions, to bioactive materials, to cellulose-based materials, and to ceramics and metals. , Of particular interest to technological applications is that the resolution of fluid-mediated assemblies relies on the physics of fluids, e.g., in contrast with printing, where the resolution of the print directly scales with the size of the deposition nozzle and the accuracy of the hardware directing its motion. Instead, the solids we discussed are smooth down to the limit of continuum mechanics .…”